Need activate/deactivate protocol

[ralmond]

Need a better way of telling when EABN is running than just checking the process queue.

For RUN mode:

1. Must be a signal to external processes about whether or not the process is running.
2. Must be able to request a fast stop (as soon as current records is processed) or clean stop (after all records are processed).

For Rerun model:

1. Must be able to signal process is running and when finished.
2. Must be able to request a fast stop.

Database Mode:
Add a field in Application collection add a field EAactive with logical value. The $active() method sets it to true and the $deactivate() method sets it to false. Add a field EAsignal, which can take values "run", "finish" and "halt". The $activate() method sets this to "run".

No DB Mode:
In the appropriate log directory, there is a file named "EA.XXX". The $active() method creates the file with the extension "running". If this name is changed to "finish" or "halt", then this does the appropriate signal. The $deactivate() method deletes that file.